Tunable Size and Shape Control of Platinum Nanocrystals from a Single Peptide Sequence

Nanoscale platinum architectures have been extensively studied as potential materials for applications in catalysis and fuel cells. Due to the high cost of platinum, much of the research has been geared toward developing methods to obtain monodisperse, monomorphic nanocrystals smaller than 10 nm. Peptide-mediated synthesis of inorganic materials is an attractive alternative to colloidal synthesis because it can be performed under ambient conditions and the peptides can be removed from the metal surfaces at mild pH or in the presence of enzymes. As a first step to achieve size and shape-controlled nanocrystals using peptides, we demonstrate here (a) the isolation of peptides that bind to specific crystal planes of platinum and (b) that a single peptide can produce structures ranging from sub-2 nm seed crystals to monodisperse 4 nm platinum polyhedra to 7 to 8 nm platinum cubes simply by changing the rates of metal reduction. This work demonstrates the first steps toward achieving biochemical control of platinum nanocrystal synthesis.